Think about how she treats her friends vs. how she treats you.
Friends do not consistently lie to each other about things that *are* the other person's business. Does she lie to her friends about her boyfriends? Does she manipulate them into babysitting so she can party?
Think about how you feel when you interact with your friends vs. how you feel when you interact with her.
Do you feel respected and cared about? Do your friends take an interest in your welfare?
Think about how you treat your friends?
Do you scoff at what they think is important in their lives? Do you judge and resent them? Do you look down at them?
She is not your friend. I have no idea if she can or will be. I will say that the "we'll always be friends" stuff that happens with separating and D people is generally just a stage of denial on one or both people's parts. Neither of you wanted a friend when you got together. But who knows...
